Image printing device, verifying device, and printed material

ABSTRACT

An image is split into a plurality of blocks, a feature quantity is extracted from each of the blocks, data is embedded into each of the blocks based on a difference between feature quantities of that block and at least one adjacent block, and data embedded blocks are printed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image printing device that prints animage, and more particularly to an image printing device, a verifyingdevice, and printed material that enable to prevent falsification of acertificate.

2. Description of the Related Art

Various methods have been know for preventing falsification andunauthorized use of a certificate (for example, employee identificationetc.). In one method, an identification code is printed on an ID card inthe form of a bar code or a Quick Response (QR) code, and theidentification code is also maintained at a control server. Whenperforming verification of the ID card, the identification code printedon the ID card is read and transmitted to the control server. If theread identification code is maintained in the control server, it isdetermined that the ID card is authentic.

In another method, a photograph of the face of the possessor of an IDcard is printed on the ID card. When a person presents an ID card, it isdetermined from the photograph printed on the ID card whether the personis an authentic possessor of the ID card. Integrated Circuit (IC) IDcards that carry a photograph of the face of the possessor of the cardprinted thereon have appeared in market. When a person presents such anIC ID-card, it is determined whether that person is an authenticpossessor of the IC-ID card based on the photograph printed on the IC-IDcard and data recorded in the IC ID-card.

Japanese Patent Laid-Open Publication No 2001-94755 discloses invisiblyembedding security data in a background portion of a main image (afacial image of the user etc.), thereby enabling to determine whetherthe certificate is authentic. When embedding data, first the backgroundportion and other portion of an original image are separated, then thesecurity data is embedded into the background portion, and finally thesecurity data embedded background portion and the other portion arecombined to obtain an image for printing on an IC ID-card. This processprevents deterioration of the image due to embedding of the securitydata.

However, the conventional methods are not very reliable; because, thebar code printed on the certificate can be easily falsified or thefacial photograph affixed to the certificate can be easily replaced,whether the certificate is authentic cannot be determined accurately.

When determining whether the certificate is authentic for a certificatethat does not include a facial photograph specifying the user, theverifying device determines whether the certificate is authentic byusing only the bar code or the QR code that is printed on thecertificate. The bar code or the QR code is a standardized code and canbe easily falsified by an unauthorized user.

When determining whether the certificate is authentic for the IC cardcertificate with a photograph, an unauthorized user can illegally gethold of the IC card certificate with the photograph and replace thephotograph on the IC card certificate with his or her own photograph.Thus, the unauthorized user can easily pass off as the IC cardcertificate holder.

In the technology disclosed in Japanese Patent Laid-Open Publication No2001-94755, because the security data is embedded only in the backgroundportion of an image, the image processing device cannot determinewhether a falsification such as cutting part of other portion, which isthe main portion in the image, has been carried out.

There is a need of a realibale and easy technique to preventfalsification of ID cards.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least partially solve theproblems in the conventional technology.

According to an aspect of the present invention, an image printingdevice includes a splitting unit that splits an image into a pluralityof blocks; a feature-quantity extracting unit that extracts a featurequantity of each of the blocks; an embedding unit that embeds data intoeach of the blocks based on a difference between feature quantities ofthat block and at least one adjacent block; and a printing unit thatprints data embedded blocks to obtain a data embedded image.

According to another aspect of the present invention, a verifying devicethat determines whether data is embedded into an image includes anextracting unit that extracts a face portion from an image of a head ofa person; and a determining unit that determines whether data isembedded into the facial portion extracted by the extracting unit.

According to still another aspect of the present invention, a printedmaterial comprising an image printing portion for printing an image of ahead of a person including a face of the person, wherein the image beingdivided into a plurality of blocks and data being embedded into each ofthe blocks based on a difference between feature quantities of thatblock and at least one adjacent block.

According to still another aspect of the present invention, an imageprinting method includes splitting an image into a plurality of blocks;extracting a feature quantity of each of the blocks; embedding data intoeach of the blocks based on a difference between feature quantities ofthat block and at least one adjacent block; and printing data embeddedblocks to obtain a data embedded image.

The above and other objects, features, advantages and technical andindustrial significance of this invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a certificate printing device according toa first embodiment of the present invention;

FIG. 2 is a block diagram of a structure of a facial-image-codeembedding unit shown in FIG. 1;

FIG. 3 is a schematic of an example of block split image data;

FIG. 4 is an explanatory diagram for explaining a density modifyingprocess performed by a code forming unit shown in FIG. 3;

FIG. 5 is a schematic of an example of a certificate that is printed bya printing device shown in FIG. 1;

FIG. 6 is a flowchart of a process performed by the certificate printingdevice shown in FIG. 1;

FIG. 7 is a block diagram of a certificate printing device according toa second embodiment of the present invention;

FIG. 8 is a flowchart of a process performed by the certificate printingdevice shown in FIG. 7;

FIG. 9 is a block diagram of a verifying device according to a thirdembodiment of the present invention;

FIG. 10 is a flowchart of a process performed by the verifying deviceaccording shown in FIG. 9;

FIG. 11 is a block diagram of a verifying device according to avariation of the third embodiment;

FIG. 12 is a block diagram of a verifying device according to a fourthembodiment of the present invention;

FIG. 13 is an example of the data structure of verification data;

FIG. 14 is a flowchart of a process performed by the verifying deviceshown in FIG. 12; and

FIG. 15 is a schematic of a computer that realizes the methods accordingto the above embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are explained next withreference to the accompanying drawings.

First, a salient feature of the present invention is explained bycomparing the present invention with the conventional technology.

When codes are embedded into an image by using the conventionaltechniques, the code causes severe deterioration of the image.

Therefore, in the conventional technology, codes were embedded only intothe background portion of the image and codes were not embedded in thefacial area so that the facial area does not deteriorate. However, inthis case, because no codes were embedded in the facial area of theimage, it is possible to falsify an ID card by pasting another facialarea on the original facial area. The present invention presents atechnique that prevents image deterioration even when codes are embeddedinto the image. This technique uses a difference between averagedensities of the image to embed codes into the image, and codes forverifying the user are embedded into the entire image including thefacial area. As a result, it becomes impossible to falsify the ID card.

A structure of a certificate printing device according to a firstembodiment is explained next. In the first embodiment, the certificateprinting device is implimented by using an image printing device. FIG. 1is a block diagram of a certificate printing device 100 according to thefirst embodiment. The certificate printing device 100 includes afacial-image-code embedding unit 110 and a printing process unit 120.The certificate printing device 100 is connected to an image inputdevice 50, an input device 60, and a printing device 70.

The image input device 50 scans the image that is traced (printed) on apaper or a film to fetch image data and inputs the fetched image datainto the certificate printing device 100. The image input device 50according to the first embodiment mainly fetches facial image data forusing in the certificate (the facial image data includes not only animage of the user's facial area, but also an image of the neck and thetorso of the user, a background etc.) from a photograph for thecertificate etc., and inputs the fetched facial image data into thecertificate printing device 100.

The input device 60 is an input device such as a keyboard. A controllerof the certificate printing device 100 uses the input device 60 to inputcodes that are embedded into the facial image data and user data that isprinted in the certificate (name of the user corresponding to the facialimage data, designation of the user etc.). The printing device 70 printsimage data that is output from the certificate printing device 100.

Returning to the certificate printing device 100, the facial-image-codeembedding unit 110 embeds codes fetched from the input device 60 in thefacial image data fetched from the image input device 50. Thefacial-image-code embedding unit 110 embeds a 16-bit code eight timesinto the facial image data to generate facial image data having encodedcodes. The facial image data is image data generated in a predeterminedformat such as Joint Photographic Expert Group (JPEG), GraphicInterchange Format (GIF) etc. and has a size of 1024 by 1024 pixels. A16-bit code such as 1010110101001010 is embedded into the facial imagedata.

A structure of the facial-image-code embedding unit 110 is explained indetail next. FIG. 2 is a detailed block diagram of the facial-image-codeembedding unit 110. The facial-image-code embedding unit 110 includes ablock splitting unit 111, a block extracting unit 112, an averaging unit113, a comparing unit 114, and a code forming unit 115.

The block splitting unit 111 inputs the facial image data, splits thefacial image data into blocks of N lines and M rows (In the firstembodiment, N=16 and M=16), and outputs the facial image data as blocksplit image data I1. FIG. 3 is a schematic of an example of the blocksplit image data I1. As shown in FIG. 3, for the sake of convenience,the example of the block split image data is indicated by using an imageother than a facial image (the facial image data is similarly split asthe block split image data shown in FIG. 3 by the block splitting unit110).

As shown in FIG. 3, the block split image data I1 includes 256 blocks(16 lines and 16 rows) such as blocks B_(l11), B_(r11), . . . , B_(l18),B_(r18), B_(l21), B_(r21), . . . , B_(l168), B_(r168) and so on. Asingle block has a size of 64 by 64 pixels. In the block split imagedata I1, 1-bit code is embedded into a pair block (two adjacent blocks).

To be specific, the pair blocks are formed of two blocks such as blocksB_(l11) and B_(r11), blocks B_(l12) and B_(r12), . . . , blocks B_(l18)and B_(r18) (forming the first line), blocks B_(l21), and B_(r21), . . ., blocks B_(l28) and B_(r28) (forming the second line), . . . , blocksB_(l161), and B_(r161), . . . , blocks B_(l168) and B_(r168) (formingthe sixteenth line).

In a block B_(lxy) of a pair block, a subscript 1 indicates that theblock B_(lxy) is a left block, a subscript x indicates a line (N), and asubscript y indicates a row (M). Similarly, in a block B_(rxy) of thepair block, a subscript r indicates that the block B_(rxy) is a rightblock, a subscript x indicates a line (N), and a subscript y indicates arow (M).

Further, in a pair block, a feature quantity in the form of an averagedensity level (average grayscale of each pixel in the block is between 0and 255) of the left block B_(lxy) is indicated by a left averagedensity data D_(l). An average density level (feature quantity) of theright block B_(rxy) is indicated by a right average density data D_(r).

As shown in the following relational expression, if the left averagedensity data D_(l) is less than the right average density data D_(r),1-bit code of the pair block is represented as 0. If the left averagedensity data D_(l) is greater than the right average density data D_(r),1-bit code of the pair block is represented as 1.D_(l<D) _(r)→0D_(l≧D) _(r)→0

For example, as shown in FIG. 3, in a pair block consisting of blocksB_(l18) and B_(r18), because a left average density data B_(l18) is 115and a right average density data B_(r18) is 125, 1-bit code of the pairblock is represented by 0.

Similarly, in a pair block consisting of blocks B_(l28) and B_(r28),because a left average density data B_(l28) is 125 and a right averagedensity data B_(r28) is 115, 1-bit code of the pair block is representedby 1.

In the block split image data I1, because a single line includes eightpair blocks (16 blocks), one line is represented by an 8-bit code. Thus,all the lines (16 lines) in the block split image data I1 arerepresented by 128-bit codes. In the first embodiment, because codes C,which are embedded into the block split image data I1 include 16 bits,the codes C can be embedded into the block split image data I1 a maximumeight times (128 divided by 16).

Returning to FIG. 2, the block extracting unit 112 sequentially extractspair blocks (block B_(lxy) and block B_(rxy)) according to bit shift ofthe codes C, and sequentially outputs density distributions of the blockB_(lxy) and the block B_(rxy) as block density data D.

Bit shift of the codes C indicates bit by bit shifting of bit pointersof the codes C from a bit at the extreme left (1) towards a bit at theextreme right (0) of the codes C.

The averaging unit 113 computes the left average density data D_(l)corresponding to the block B_(lxy) and the right average density dataD_(r) corresponding to the block B_(rxy) from the block density data D.

The comparing unit 114 compares n-th bit of the codes C (such that n=1,2, . . . , 16 beginning from the bit at the extreme left) with a bitdetermination result that is determined from a magnitude relationbetween the left average density data D_(l) and the right averagedensity data D_(r) (based on the aforementioned relational expression,bit is determined as 0 or 1).

Based on the comparison result of the comparing unit 114, the codeforming unit 115 embeds the codes C into the block split image data I1(the facial image data). To be specific, if the comparison result of thecomparing unit 114 is matching, the code forming unit 115 maintains themagnitude relation between the left average density data D_(l) and theright average density data D_(r). If the comparison result of thecomparing unit 114 is not matching, the code forming unit 115 carriesout a density modifying process to modify (reverse the magnituderelation) the left average density data D_(l) and the right averagedensity data D_(r) such that the magnitude relation between the leftaverage density data D_(l) and the right average density data D_(r)represents bits of the codes C, generates facial image data having theencoded codes (hereinafter, “encoded facial image data”), and outputsthe encoded facial image data.

FIG. 4 is a schematic for explaining the density modifying processperformed by the code forming unit 115. In the density modifyingprocess, if D_(l) is less than D_(r), a left average density data D′_(l)after modification is computed by using the expression (1) (see FIG. 4),and a right average density data D′_(r) after modification is computedby using the expression (2). T indicates a level difference between thepair block, and has a value such as 30. Due to this, after densitymodification, the left average density data D′_(l) becomes less than theright average density data D′_(r), and the bit determination result ischanged from 1 to 0.

If D_(l) is greater than or equal to D_(r), a left average density dataD′_(l) after modification is computed by using the expression (3), and aright average density data D′_(r) after modification is computed byusing the expression (4). Due to this, after density modification, theleft average density data D′_(l) becomes greater than the right averagedensity data D′_(r), and the bit determination result is changed from 0to 1.

Generally, facial image includes a large amount of yellow colorcomponent. Thus, embedding the aforementioned codes into the facialimage data by using the yellow color component enables to carry out dataembedding such that deterioration of the image is less noticeable. Anexample of code embedding using the yellow color component is explainednext.

The facial image data includes data pertaining to colors in a Red GreenBlue (RGB) format. According to a relation pertaining to complementarycolors, the yellow color component is represented by B from the RBGformat. Thus, when extracting the split block density data D, the blockextracting unit 112 takes average grayscale pertaining to B as the blockdensity data D, and the averaging unit 113 computes the right averagedensity data and the left average density data from the block densitydata D (average density data pertaining to B is represented by B averagedensity data). The comparing unit 114 compares B average density datapertaining to an adjacent block pair.

If the magnitude relation pertaining to B average density data of theblock pair is matching with the code for embedding, for example, ifright B average density data is greater than left B average density datawhen embedding the code 0 into the block pair, the code forming unit 115maintains the magnitude relation between the right B average densitydata and the left B average density data.

If the magnitude relation pertaining to B average density data of theblock pair is not matching with the code for embedding, for example, ifthe right B average density data is less than the left B average densitydata when embedding the code 0 into the block pair, the code formingunit 115 reverses the magnitude relation between the right B averagedensity data and the left B average density data.

Returning to FIG. 1, the printing process unit 120 fetches the encodedfacial image data from the facial-image-code embedding unit 110, fetchescodes and the user data from the input device 60, and based on thefetched data generates certificate data. The certificate data includesthe encoded facial image data, codes, and the user data. The printingprocess unit 120 inputs the generated certificate data into the printingdevice 70 and causes the printing device 70 to print the certificate.FIG. 5 is a schematic of an example of a certificate printed by theprinting device 70.

A process performed by the certificate printing device 100 according tothe first embodiment is explained next. FIG. 6 is a flowchart of theprocess performed by the certificate printing device 100. Thefacial-image-code embedding unit 110 of the certificate printing device100 fetches the facial image data from the image input device 50 (stepS101) and fetches the codes for embedding from the input device 60 (stepS102).

Next, the facial-image-code embedding unit 110 embeds the codes forembedding into the facial image data (step S103), and distributes theencoded facial image data to the printing process unit 120 (step S104).The printing process unit 120 fetches the encoded facial image data,codes and the user data (step S105).

The printing process unit 120 generates the certificate data from theencoded facial image data, the codes, and the user data (step S106),outputs the certificate data to the printing device 70, and causes theprinting device 70 to print the certificate (step S107).

Thus, the facial-image-code embedding unit 110 embeds the codes forembedding into the facial image data that includes the facial area,based on the facial image data that includes the embedded codes, theprinting process unit 120 generates the certificate data, and causes theprinting device 70 to print the certificate, thereby enabling to preventfalsification pertaining to the certificate.

Thus, in the certificate printing device 100, the facial-image-codeembedding unit 110 embeds codes into the facial image data fetched fromthe image input device 50 using a difference between the averagedensities of the facial image data to generate the encoded facial imagedata, thereby enabling to prevent image deterioration due to embeddingof codes into an image. The printing process unit 120 uses the encodedfacial image data to generate the certificate data, outputs thegenerated certificate data to the printing device 70, and causes theprinting device 70 to print the certificate, thereby enabling to preventfalsification of certificates.

A salient feature of a certificate printing device according to a secondembodiment is explained next. The certificate printing device accordingto the second embodiment extracts the user's facial area that isincluded in the facial image, trims the facial image such that thefacial area represents more than a predetermined percentage (greaterthan 50 percent) of the entire image, and embeds codes into the trimmedfacial image. Next, the certificate printing device prints the facialimage having the embedded codes as the certificate.

Thus, the certificate printing device according to the second embodimenttrims the facial image such that the user's facial area represents morethan the predetermined percentage of the facial image, embeds codes intothe trimmed facial image, and uses the facial image as the certificate,thereby enabling to prevent falsification pertaining to the certificateand enabling to accurately determine whether the certificate isauthentic.

A structure of the certificate printing device according to the secondembodiment is explained next. FIG. 7 is a schematic of the structure ofa certificate printing device 200 according to the second embodiment.The certificate printing device 200 includes a facial area extractingunit 210, an image cutting unit 220, a facial-image-code embedding unit230, and a printing process unit 240. The certificate printing device200 is connected to the image input device 50, the input device 60, andthe printing device 70. Because the image input device 50, the inputdevice 60, and the printing device 70 are similar to the image inputdevice 50, the input device 60, and the printing device 70 that areshown in FIG. 1 respectively, the explanation is omitted.

The facial area extracting unit 210 fetches the facial image data fromthe image input device 50, and extracts the user's facial area that isincluded in the fetched facial image data. A facial part detectingmethod disclosed in Japanese Patent Specification No 2000-132688 can beused, for example, as a method to extract the facial area. In the facialpart detecting method, existence probability pertaining to facial partsin various pixel locations of the input image is computed from the inputimage by using template matching and probability distribution pertainingto the prior learnt facial parts is computed from sample data. Pointswhere the existence probability and the probability distributionincrease together are detected as the facial parts. The facial areaextracting unit 210 distributes data pertaining to the extracted facialarea (hereinafter, “facial area data”) and the facial image data to theimage cutting unit 220.

The image cutting unit 220 fetches the facial image data and the facialarea data from the facial area extracting unit 210 and cuts the facialimage such that the facial area represents more than 50 percent of thefacial image. The image cutting unit 220 distributes data pertaining tothe cut facial image to the facial-image-code embedding unit 230.

Because the facial-image-code embedding unit 230 and the printingprocess unit 240 are similar to the facial-image-code embedding unit 110and the printing process unit 120 shown in FIG. 1 respectively, theexplanation is omitted.

A process performed by the certificate printing device 200 is explainednext. FIG. 8 is a flowchart of the process performed by the certificateprinting device 200. As shown in FIG. 8, the image area extracting unit210 of the certificate printing device 200 fetches the facial image datafrom the image input device 50 (step S201) and extracts the facial area(step S202).

The image cutting unit 220 fetches the facial image data and the facialarea data from the facial area extracting unit 210, trims the facialimage such that the facial area represents more than 50 percent of theentire facial image, and distributes the trimmed facial image data tothe facial-image-code embedding unit 230 (step S203).

The facial-image-code embedding unit 230 fetches the codes for embeddingfrom the input device 60 (step S204), embeds the codes for embeddinginto the facial image data (step S205), and distributes the encodedfacial image data to the printing process unit 240 (step S206).

The printing process unit 240 fetches the encoded facial image data, thecodes and the user data (step S207), generates the certificate data fromthe fetched data (step S208), outputs the generated certificate data tothe printing device 70 and causes the printing device 70 to print thecertificate (step S209).

Thus, the facial area extracting unit 210 extracts the facial area, theimage cutting unit 220 trims the facial image such that the facial arearepresents more than 50 percent of the entire facial image, and thefacial-image-code embedding unit 230 embeds the codes for embedding intothe trimmed facial image data, thereby enabling to prevent imagedeterioration and to generate printed material that enables to determinewhether the printed material is authentic.

Thus, in the certificate printing device 200, the facial area extractingunit 210 extracts the facial area from the facial image data, the imagecutting unit 220 trims the facial image such that the facial arearepresents more than 50 percent of the entire facial image, thefacial-image-code embedding unit 230 embeds the codes into the trimmedfacial image data by using a difference between average densities togenerate the encoded facial image data, the printing process unit 240uses the encoded facial image data to generate the certificate data,outputs the generated certificate data to the printing device 70, andcauses the printing device 70 to print he certificate, thereby enablingto prevent image deterioration and prevent falsification by replacementof the facial portion.

A salient feature of a verifying device according to a third embodimentof the present invention is explained next. The verifying deviceaccording to the third embodiment extracts the user's facial areaincluded in the facial image and determines whether the extracted facialarea includes data (codes). Thus, extracting the facial area from thefacial image and determining whether the extracted facial area includesdata enables to accurately determine whether the certificate isauthentic.

A structure of the verifying device according to the third embodiment isexplained next. FIG. 9 is a block diagram of the structure of averifying device 300 according to the third embodiment. The verifyingdevice 300 includes a facial image area extracting unit 310 and a dataverifying unit 320. The verifying device 300 is connected to the imageinput deice 50 and a display device 80. Because the image input device50 is similar to the image input device 50 shown in FIG. 1, theexplanation is omitted. The display device 80 is a display device suchas a display.

The facial image area extracting unit 310 fetches the facial image datafrom the image input device 50 and extracts the user's facial area fromthe fetched facial image data. A method similar to the method that isused by the facial area extracting unit 210 in the second embodiment canbe used to extract the facial area. The facial image area extractingunit 310 distributes the extracted facial area data and the facial imagedata to the data verifying unit 320.

The data verifying unit 320 fetches the facial image data and the facialarea data from the facial image area extracting unit 310 and determineswhether codes are embedded into the facial area of the facial image. Inother words, the data verifying unit 320 splits the facial image intomultiple blocks and based on the average density difference between theadjacent blocks extracts the codes that are embedded into the facialarea.

If codes are embedded into the facial area of the facial image, the dataverifying unit 320 outputs in the display device 80 a notificationstating that codes are embedded into the facial area. If codes are notembedded into the facial area of the facial image, the data verifyingunit 320 outputs in the display device 80 a notification stating thatcodes are not embedded into the facial area.

A specific process that is used by the data verifying unit 320 todetermine whether codes are embedded into the facial area of the facialimage is explained next. If the facial image that is input into theimage input device 50 is officially encoded by the certificate printingdevice 100 and the certificate printing device 200 that are explained inthe first and the second embodiments respectively, codes and errorcorrecting values pertaining to the codes are repeatedly embedded assets into the facial area of the facial image. Although not explained inthe first and the second embodiments, during encoding, the certificateprinting devices 100 and 200 repeatedly embed the codes and the errorcorrecting values as sets into the facial area. The data verifying unit320 fetches multiple codes and the error correcting values that areembedded into the facial area and corrects each code by using thecorresponding error correcting value.

Next, the data verifying unit 320 carries out a majority selection usingthe corrected multiple codes to determine the codes. For example, if thecorrected codes are 101, 101, and 111, based on a result of the majorityselection, 101 is determined as the code embedded into the facial area.If the data verifying unit 320 is able to determine the codes from thefacial area, the data verifying unit 320 determines that the certificateinput from the image input device 50 is not falsified.

If the facial image input into the image input device 50 is falsified(not officially encoded), codes and the error correcting values are notembedded as sets into the facial area, and the data verifying unit 320cannot determine the codes from the facial area by using theaforementioned method (even if numerical values from the falsifiedfacial image are read using the average density difference, thenumerical values are random and the data verifying unit 320 cannotdetermine the codes by using the aforementioned majority selection).Thus, the data verifying unit 320 determines that the certificate inputfrom the image input device 50 is falsified.

A process performed by the verifying device 300 is explained next. FIG.10 is a flowchart of the process performed by the verifying device 300.As shown in FIG. 10, the facial image area extracting unit 310 of theverifying device 300 fetches the facial image data from the image inputdevice 50 (step S301) and extracts the facial area (step S302).

The data verifying unit 320 determines whether codes are embedded intothe facial area (step S303) and outputs a determination result in thedisplay device 80 (step S304).

Thus, the facial image area extracting unit 310 extracts the user'sfacial area included in the facial image, and the data verifying unit320 determines whether data is embedded into the facial area, therebyenabling to accurately determine whether the certificate is authentic.

Thus, in the verifying device 300, the facial image area extracting unit310 fetches the facial image data from the image input device 50 andextracts the facial area. The data verifying unit 320 determines whethercodes are embedded into the facial area, and outputs the determinationresult in the display device 80, thereby enabling to accuratelydetermine whether the-certificate is authentic.

It has, been explained above that the verifying device 300 displays thedetermination result using the display device. However, thedetermination result can be notified to the controller etc. using sound.FIG. 11 is a block diagram of a variation of the verifying device 300that includes a speaker.

As shown in FIG. 11, the data verifying unit 320 outputs thedetermination result in the display device 80 and also notifies thedetermination result to the controller using the speaker. For example,if codes are embedded into the facial area, the data verifying unit 320causes a speaker 90 to output a sound, and if codes are not embeddedinto the facial area, the speaker 90 does not output a sound.

Thus, notifying the determination result to the controller by a soundfrom the speaker 90 greatly reduces a burden on the controller to checkwhether the certificate is authentic.

A salient feature of a verifying device according to a fourth embodimentof the present invention is explained next. The verifying deviceaccording to the fourth embodiment extracts the user's facial areaincluded in the facial image and reads the codes embedded into theextracted facial image. Next, the verifying device determines whetherthe read codes are matching with codes that are stored beforehand in astorage unit, thereby determining whether the certificate is valid.

Thus, the verifying device according to the fourth embodiment readscodes from the facial area and determines whether the read codes arematching with the codes that are stored beforehand in the storage unit.Modifying the codes that are stored in the storage unit enables thecontroller to prevent falsification of the image pertaining to thecertificate and also enables to easily invalidate the certificate of aretired employee.

A structure of the verifying device according to the fourth embodimentis explained next. FIG. 12 is a block diagram of the structure of averifying device 400 according to the fourth embodiment. The verifyingdevice 400 includes a facial image area extracting unit 410, a dataverifying unit 420, a data determining unit 430, a storage unit 440, andan updation processor 450. The verifying device 400 is connected to theimage input device 50, the input device 60, and the display device 80.

Because the image input device 50 and the display device 80 are similarto the image input device 50 and the display device 80 that are shown inFIG. 9 respectively, the explanation is omitted. The input device 60 isan input device such as a keyboard etc. In the fourth embodiment, thecontroller uses the input device 60 to input verification data thatverifies data embedded into the facial image. The controller of theverifying device 400 gets data pertaining to the codes that are embeddedinto the facial image data from the controller of the certificateprinting devices 100 and 200 that are explained in the first and thesecond embodiments respectively, and inputs the verification data intothe input device 60.

Similarly as the facial image area extracting unit 310, the facial imagearea extracting unit 410 fetches the facial image data from the imageinput device 50, and extracts the user's facial area from the fetchedfacial image data. The facial image area extracting unit 410 distributesthe extracted facial area data and the facial image data to the dataverifying unit 420.

The data verifying unit 420 fetches the facial image data and the facialarea data from the facial image area extracting unit 410 and extractsthe codes embedded into the facial area of the facial image. The dataverifying unit 420 splits the facial image into multiple blocks andbased on the average density difference pertaining to the adjacentblocks extracts the codes that are embedded into the facial area. Thedata verifying unit 420 distributes the extracted codes to the datadetermining unit 430.

The data determining unit 430 fetches the codes from the data verifyingunit 420, determines whether the fetched codes are included inverification data 440 a that is stored in the storage unit 440, andoutputs the determination result in the display device 80. Theverification data 440 a is data for verifying the codes that areembedded into the facial image data. FIG. 13 is a schematic of anexample of a data structure of the verification data. The certificate isvalid if the codes included in the verification data 440 a are embeddedinto the facial image area.

If the codes included in the verification data 440 a are extracted fromthe facial area of the facial image, the data determining unit 430determines that the certificate having the affixed facial image isvalid. If the codes included in the verification data 440 a are notextracted from the facial area of the facial image, the data determiningunit 430 determines that the certificate having the affixed facial imageis invalid.

Upon fetching verification data from the input device 60, the updationprocessor 450 uses the fetched verification data to update theverification data 440 a stored in the storage unit 440. To preventunauthorized updation of the verification data 440 a, the updationprocessor 450 can fetch a password from the input device 60 and updatethe verification data if the fetched password is accurate.

In the fourth embodiment, the verifying device 400 fetches verificationdata from the input device 60 and the updation processor 450 updates theverification data 440 a stored in the storage unit 440. However, theverifying device 400 can also fetch verification data via a network froma control server etc. that controls the verification data and update theverification data 440 a stored in the storage unit 440.

A process performed by the verifying device 400 is explained next. FIG.14 is a flowchart of the process performed by the verifying device 400.As shown in FIG. 14, the facial image area extracting unit 410 of theverifying deice 400 fetches the facial image data from the image inputdevice 50 (step S401) and extracts the facial area (step S402).

The data verifying unit 420 extracts the codes embedded into the facialarea (step S403). The data determining unit 430 determines whether thecodes embedded into the facial area are included in the verificationdata 440 a (step S404) and outputs the determination result in thedisplay device 80 (step S405).

Thus, the facial image area extracting unit 410 extracts the facialarea, the data verifying unit 420 extracts the codes embedded into thefacial area, and the data determining unit 430 determines whether thecodes embedded into the facial area are included in the verificationdata 440 a, thereby enabling to accurately determine whether thecertificate is authentic and also enabling to determine whether thecertificate is valid.

Thus, in the verifying device 400, the facial image area extracting unit410 fetches the facial image data from the image input device 50 andextracts the facial area. The data verifying unit 420 extracts the codesembedded into the facial area, and data determining unit 430 determineswhether the codes embedded into the facial area are included in theverification data 440 a, thereby enabling to prevent falsification ofthe certificate and also enabling to easily modify the validity of thecertificate.

A certificate printing device and a verifying device that use averagedensity are explained in the first through the fourth embodiments.However, the present invention is not to be thus limited, and can besimilarly applied to a certificate printing device and a verifyingdevice that use other feature quantities related to image such as amountof granulation, color saturation, density equilibrium, dispersion etc.

The certificate printing device and the verifying device that use theaverage density difference between the pair blocks are explained in thefirst through the fourth embodiments. However, the present invention isnot to be thus limited, and can be similarly applied to a certificateprinting device and a verifying device that use the average densitydifference of other combinations of blocks.

Each process performed by the certificate printing device or theverifying device can be realized by causing a computer to execute aprogram related to a code embedding process or a code verifying process.An example of the computer which executes a code embedding program and acode verifying program that include functions similar to the certificateprinting device and the verifying device explained in the aforementionedembodiments is explained with reference to FIG. 15. FIG. 15 is aschematic of the computer that executes the code embedding program andthe code verifying program.

As shown in FIG. 15, a computer 600 includes an input output interface610, a Random Access Memory (RAM) 620, a Hard Disk Drive (HDD) 630, aRead Only Memory (ROM) 640, and a Central Processing Unit (CPU) 650 thatare connected by buses 660. The input output interface 610 is aninterface for connecting an input device such as a keyboard, an imageinput device and a display device such as a scanner, and an outputdevice such as a printer, a speaker etc.

If the computer 600 is the certificate printing device, the ROM 640stores the code embedding program that includes functions similar to thecertificate printing devices 100 and 200 explained in the embodiments.In other words, as shown in FIG. 15, the ROM 640 stores beforehand acode embedding program 640 a.

As shown in FIG. 15, the CPU 650 reads the code embedding program 640 afrom the ROM 640 and executes the read code embedding program 640 a,thereby causing the code embedding program 640 a to function as a codeembedding process 650 a. The CPU 650 embeds codes into the facial areaof the facial image, generates the certificate data, and causes theprinter to print the certificate.

If the computer 600 is the verifying device, the ROM 640 stores thereinthe code verifying program that includes functions similar to theverifying devices 300 and 400 explained in the embodiments. In otherwords, as shown in FIG. 15, the ROM 640 stores beforehand a codeverifying program 640 b.

As shown in FIG. 15, the CPU 650 reads the code verifying program 640 bfrom the ROM 640 and executes the read code verifying program 640 b,thereby causing the code verifying program 640 b to function as a codeverifying process 650 b. The CPU 650 reads from the RAM 620 verificationdata 630 a that is stored in the HDD 630, determines whether codesembedded into the facial area are included in the verification data 620,and displays the determination result in the display device.

According to an aspect of the present invention, it becomes possible toprevent severe image deterioration due to embedding of data, therebymaking falsification of certificates difficult.

Although the invention has been described with respect to a specificembodiment for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

1. An image printing device comprising: a splitting unit that splits animage of a head of a person including a face of the person into aplurality of blocks; a feature-quantity extracting unit that extracts anaverage density of yellow component of each of the blocks; an embeddingunit that embeds data into each of the blocks based on a differencebetween average densities of yellow component of that block and at leastone adjacent block; and a printing unit that prints data embedded blocksto obtain a data embedded image.
 2. The image printing device accordingto claim 1, further comprising an extracting unit that extracts aspecific region from the image such that an area of the specific regionexceeds a predetermined percentage of the image, wherein the splittingunit splits the specific region into a plurality of blocks, thefeature-quantity extracting unit extracts a feature quantity of each ofthe blocks, the embedding unit embeds data into each of the blocks basedon a difference between feature quantities of that block and at leastone adjacent block.
 3. The image printing device according to claim 2,where the specific region is face.
 4. A verifying device that determineswhether data is embedded into an image, the verifying device comprising:an extracting unit that extracts an image of a facial portion of aperson from an image of a head of the person; a determining unit thatdetermines whether data is embedded into the facial portion extracted bythe extracting unit; a storing unit that stores therein uniqueverification data; a data extracting unit that, upon the determiningunit determining that data is embedded into the facial portion, extractsdata embedded into the facial portion; and a verifying unit thatcompares data extracted by the data extracting unit with theverification data in the storing unit and determines that the facialportion corresponds to a face of an authentic user when there is matchbetween the data extracted by the data extracting unit and theverification data.
 5. The verifying device according to claim 4, furthercomprising an output unit that outputs a result of determinationobtained by the determining unit.
 6. A printed material comprising animage printing portion for printing an image of a head of a personincluding a face of the person, an area of the face exceeding apredetermined percentage of an area of the image, wherein the image isdivided into a plurality of blocks and data is embedded, by a processor,into each of the blocks based on a difference between feature quantitiesof that block and at least one adjacent block.
 7. The printed materialaccording to claim 6, wherein the feature quantity is average density ofyellow component.
 8. An image printing method comprising: splitting,using a processor, an image of a head of a person including a face ofthe person into a plurality of blocks; extracting, using a processor, anaverage density of yellow component of each of the blocks; embedding,using a processor, data into each of the blocks based on a differencebetween average densities of yellow component of that block and at leastone adjacent block; and printing, using a processor, data embeddedblocks to obtain a data embedded image.